Diglycidyl ethers of TBBA are known in the art and have a wide varietv of applications, such as: raw materials for self-extinguishing epoxy laminates, flame retardants for phenolic laminates and for thermoplastic materials, raw materials for modified epoxy resins, and high molecular weight epoxy resins, powder coatings, dry epoxy molding compounds, heat stabilizers for halogenated organic compounds, and so forth.
The lower the molecular weight of the brominated epoxy resins, based on tetrabromobisphenol A, the lower their softening points are. For example, when the molecular weight decreases from 4,000 to 700 g/mol, the softening point decreases from 160.degree. C. to 55.degree. C. The handling and the transportation of low softening point or semi-solid materials are both complicated and expensive, since such materials tend to stick to their containers. In some uses, such as in powder coating and solid molding compounds, there is a need for high softening point materials with high concentrations of epoxy groups, viz. with low molecular weight. It is possible, in principle, to raise the softening point by the use of additives, such as materials having a high surface area, but the presence of such material is not always acceptable, and anyway, their ability to raise to the softening point is limited.
It is a purpose of this invention to provide brominated epoxy resins based on TBBA, and specifically, diglycidyl ethers of TBBA, having a low molecular weight and a higher softening point than materials of the same molecular weight known in the prior art.
It is another purpose of this invention to provide such resins having a specific crystalline structure.
It is a further purpose of this invention to provide such resins with a high flowability in the particulate solid state (powder or flakes), that are easy to package and to transport in bulk or bags.
It is a still further purpose of this invention to provide a method for producing such resins, which is economical and has a substantially quantitative yield.
It is a still further purpose of this invention to provide a method which has a very high and practically quantitative yield.
Other purposes and advantages of this invention will appear as the description proceeds.